1. Field of the Invention
Apparatuses consistent with exemplary embodiments relate to a power supply apparatus and a display apparatus including the same, and more particularly, to a power supply apparatus which may adjusts a power factor correction circuit to manage power efficiently and a display apparatus applying the same.
2. Description of the Related Art
In general, a power supply apparatus having a module which converts electricity provided from an external source to be suitable for supply to various electric apparatuses, such as a computer, a television, a video cartridge recorder, a converter, and a wireless communication apparatus, performs voltage control and relieves impact on high frequency that is higher than commercial frequency using semiconductor switching properties.
A power supply apparatus may be a liner power supply or a switching mode power supply (SMPS). The SMPS has been widely used in many electronic products as a main power supply since the 1990s since the SMPS is considered better for use in small apparatus and more efficient than the linear power supply.
The electric power supplied by a power supply apparatus is the product of voltage and current. The electric power includes active power, reactive power and apparent power. The apparent power is the product of voltage and current, and the active power represents actual power considering phase difference (A) between voltage and current due to a coil or a condenser during current alternation.
In the case of active power, only current in the same direction as voltage (=current*COS θ) is actually applied. Accordingly, active power is voltage*(current*COS θ). Herein, COS θ is a power factor.
Reactive power is the product of current in the direction of 90 degrees with respect to voltage (=current*SIN θ) and voltage, and occupies part of capacity of an apparatus, doing nothing and consuming no power. Herein, SIN θ is a reactive power factor.
Power factor is the ratio of active power with respective apparent power, and represents how effectively voltage and current work in an electric apparatus.
If the power factor is high, that means active power is close to apparent power, and an electric apparatus is being utilized most efficiently from the perspective of a load (a receptor). The efficiency of power facility is also great from the perspective of a power supply (a supplier) since the supplier may release less current to the same load and thus, less voltage drop occurs.
A power factor correction (PFC) circuit is employed to perform power factor correction. However, since the PFC circuit always operates as long as power is supplied, the output efficiency of a power supply apparatus is low. Therefore, a method for enhancing output efficiency is required to reduce power consumption considering that the PFC circuit is provided in most electric products.